1. Field of the Invention
The present invention relates to an engine with a torque converter, and more particularly, to an engine with a torque converter mounted on an all terrain saddle-seat vehicle.
2. Description of the Background Art
FIG. 6 to FIG. 8 are views of a first example of a conventional art. FIG. 6 is a front view of an engine for a conventional vehicle, illustrating an inner portion of the engine with the front case cover removed. FIG. 7 is a transverse cross section of a crankcase of the engine, viewed from the front, and illustrating the positions of respective rotation axes. FIG. 8 is a sectional view taken along line Bxe2x80x94B of FIG. 7.
The engine is mounted on a vehicle via a mounting boss 008 so that respective rotation axes are approximately parallel to an advancing direction of the vehicle. In FIG. 6, reference numeral 003 denotes a front crankcase, and 004 denotes a rear crankcase, and the respective rotation axes are rotatably supported by these crankcases. Reference numeral 002 denotes a cylinder block coupled on the front and rear crankcases, which are integrally coupled with each other. Reference numeral 001 denotes a cylinder head coupled to the cylinder block 002. Reference numeral 020 denotes a crankshaft, 075 denotes a centrifugal start clutch provided on a front end of the crankshaft, 025 denotes a main shaft of a transmission, and 076 denotes a multi-disk type shift clutch provided on a front end of the main shaft. Reference numeral 028 denotes a drive shaft, and 040 denotes an oil pump.
In FIG. 7 (a transverse cross section of the crankcase, seen from the front), a crankshaft 020 extending along a traveling direction of a vehicle, viewed from the front, is arranged slightly biased on a left side from the center of the crankcase. The main shaft 025 and a countershaft 026 of the transmission are arranged in that order rightwardly of the crankshaft 020. A reverse shaft 027 is arranged above a mid-position between the main shaft 025 and the countershaft 026. The drive shaft 028 is arranged below the countershaft 026. These shafts are arranged parallel to the crankshaft 020, and rotatably supported on the front crankcase 003 and the rear crankcase 004.
A camshaft 029 driven by chains from the crankshaft 020 is arranged diagonally left of and above the crankshaft 020. A balance shaft 030 driven by gears from the crankshaft 020 is arranged below the camshaft 029. A shift drum 031 is arranged below the main shaft 025 and leftward of the drive shaft 028. The shift drum 031 is located at a central lower section inside the crankcase. The camshaft 029, balance shaft 030, and shift drum 031 are supported rotatably on the front crankcase 003 and the rear crankcase 004. Reference numeral 040 denotes an oil pump provided in front of the balance shaft 030.
FIG. 8 shows a sectional view taken on line Bxe2x80x94B of FIG. 7. A left hand side in FIG. 8 shows a front portion of the engine, and a right hand side in FIG. 8 shows a rear portion of an engine. In FIG. 8, the oil pump 040 is directly connected to an end section of the balance shaft 030, and penetrates the front crankcase 003. The oil pump 040 is provided in front of the balance shaft 030 in front of the front crankcase 003. When the engine is in an operation state, the oil pump is integrally rotatably driven with the balance shaft 030, and feeds lubricating oil to an oil filter 056. The lubricating oil passed through the oil filter 056 is fed to a lubricating section of the engine and the transmission. Reference numeral 075 denotes the centrifugal type start clutch which is located in front of the crankshaft 020.
FIG. 9 and FIG. 10 are views of a Japanese Examined Patent Publication H7-33763, and relates to a second example of the conventional art. FIG. 9 is a longitudinal cross section of the crankcase of a V type engine for a motorcycle, seen from the side. FIG. 10 is a sectional view taken along line Cxe2x80x94C of FIG. 9.
As shown in FIG. 9, a crankshaft 081, a main shaft 082, a countershaft 083, a drive shaft 084, and a shift drum 085 are arranged inside of a crankcase 080. The main shaft 082, countershaft 083, drive shaft 084, and shift drum 085 are arranged to constitute a transmission and a power transmission mechanism. All of these shaft groups are arranged in a direction perpendicular to an advancing direction of the vehicle. Reference numeral 090 denotes an oil pump provided at a position overlapping with the shift drum 085.
FIG. 10 is a transverse cross section of the crankcase, seen from the rear. In FIG. 10, reference numeral 080L denotes a left crankcase, and 080R denotes a right crankcase. FIG. 10 illustrates a state where both ends of the main shaft 082 are rotatably supported on the left and right crankcase 080L and 080R. One side surface 092 of a body 091 of the oil pump 090 is fixed to the right crankcase 080R by a bolt or the like (not illustrated). On the other side surface 093 of the body 091 of the oil pump 090, a bearing hole 094 is formed for rotatably supporting one end 086 of the shift drum 085. The other end 087 of the shift drum 085 is rotatably supported on the left crankcase 080L. A rotor 095 is installed inside the body 091 of the oil pump 090, and an oil pump shaft 096 is connected to the rotor 095. The oil pump shaft 096 penetrates the right crankcase 080R and protrudes to an outer section. A driven gear 097 is provided at the end section of the oil pump shaft 096. One end of the main shaft 082 penetrates the right crankcase 080R and protrudes to an outer section thereof. At an end section of the main shaft 082, a drive gear 088 is meshed with the driven gear 097 of the oil pump shaft 096. The oil pump 090 is driven by rotation of the main shaft 082. The shift drum 085 can be moved independently of the oil pump 090. Reference numerals 089L and 089R in FIG. 10 denote left and right side covers.
In the engine illustrated in the first example of the conventional art shown in FIGS. 6-8, the centrifugal start clutch 075 has been provided at a front end of the crankshaft 020, and a multi-disk type shift clutch 076 has been provided at a front end of the main shaft of the transmission (refer to FIG. 6). Further, the oil pump 040 has been provided at a front end of the balance shaft 030. In order to enhance performance of a conventional engine, a torque converter is provided in place of the conventional centrifugal start clutch 075. Further, in order to make an engine water cooled, a water pump is provided. When installing a double rotor type oil pump having a first rotor for feeding lubricating oil to a lubricating section and a second rotor for feeding lubricating oil to an oil cooler, the torque converter with a large diameter has occupied a space in front of the balance shaft. The space is insufficient as an installing place for the oil pump and the water pump. The oil pump and the water pump cannot be installed in front of the conventional balance shaft. Therefore, the width of the engine must be enlarged when positions of the balance shaft and the pump shaft, or the position of merely of the pump shaft, are moved laterally outward so as to avoid the torque converter.
In the engine illustrated in the second embodiment of the conventional art shown in FIGS. 9 and 10, the oil pump 090 is installed utilizing a dead space of an inner section of the crankcase, and the oil pump 090 is driven by the gear 097 outside the crankcase. If this arrangement is applied to an engine for a vehicle where a double rotor type oil pump is installed inside the crankcase, there is a drawback that for reasons of installing the oil pump inside the crankcase and having respectively oil delivery piping coming out from both rotors, the piping inside the crankcase becomes complicated. Since the gear 097 for driving the oil pump is provided along an outer face of the crankcase, the piping to the oil cooler of an outer section cannot be made straight. Further, there is a drawback that an arrangement of piping of an oil delivery route becomes further complicated when the water pump and the oil pump are coaxially arranged in order to form an engine of the water cooled type.
The present invention is directed to an engine with a torque converter, a double rotor type oil pump, and a water pump. Installation of the oil pump and the water pump is made possible by effectively utilizing the dead space at a bottom section of the engine on an outer side of the crankcase. In the present invention, the position of the oil pump is moved largely from the conventional position. Further, the length of the piping to the oil cooler and the radiator arranged in the front of the vehicle body is made to be as short as possible.
The present invention solves the problems described above, and relates to an engine with the torque converter. In the engine, the crankshaft is placed substantially in parallel to a longitudinal direction of a vehicle, and the shift drum is placed substantially in parallel to a longitudinal direction of the vehicle at a lower center section of the crankcase, and they are rotatably supported on the crankcase. Further, the torque converter is provided on one end of an extension section of the crankshaft at an outer section of the crankcase.
The oil pump is overlapped with the shift drum and the torque converter when viewed from a forward direction of the engine. The oil pump has a pump shaft in parallel to the crankshaft, and is driven by chains from the crankshaft. The oil pump is arranged in a space between an outer surface of the crankcase and the torque converter viewed in a longitudinal direction.
Since the oil pump is directly driven by a chain from the crankshaft, its position can be set independently from the other shafts. Further, piping to the oil cooler arranged in a front section of the vehicle can be made as short as possible.
In an engine with the torque converter as described above, a water pump coaxially driven by the oil pump is provided on an extension line of a shaft of the oil pump, on a side far from the torque converter as viewed from the center of the engine. Since the water pump is coaxially driven by the oil pump, a drive mechanism is simple. Since there is no equipment to get in the way of piping in front of the water pump, the length of piping to a radiator or the like arranged in a front section of the vehicle can be made as short as possible.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.